<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <title>TZ-追梦</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        li{
            list-style: none;
        }
        ul{
            width: 350px;
            height: 300px;
            margin: 100px auto;
            box-shadow: 0 0 5px #000;
            display: -webkit-flex;
            display: flex;

        }
        li{
            width: 50px;
            height: 50px;

        }

        ul li:nth-child(1){background: green;order:3;}
        ul li:nth-child(2){background: gray;order:5;}
        ul li:nth-child(3){background: purple;order:1;}
        ul li:nth-child(4){background: gold;order:4;}
        ul li:nth-child(5){background: pink;order:2;}
    </style>
</head>
<body>
    <ul>
        <li>1</li>
        <li>2</li>
        <li>3</li>
        <li>4</li>
        <li class="last">5</li>
    </ul>
</body>
</html>